1. Technical Field
The present disclosure relates to a charge pump circuit and a phase lock loop circuit having the same, in particular to a charge pump circuit and a phase lock loop circuit having the same, capable of locking phase quickly.
2. Description of Related Art
A charge pump circuit is a kind of component widely applied to circuits, in particular applied to a phase lock loop circuit. Please refer to FIG. 1 which is a schematic view of a traditional charge pump circuit. As shown in FIG. 1, a traditional charge pump circuit 10 includes an up-side current source A1, a down-side current source A2, an up-side switch UP and a down-side switch DOWN. An end of the up-side current source A1 is electrically connected to a power voltage VDD. Another end of the up-side current source A1 is sequentially connected in series with the up-side switch UP, the down-side switch DOWN, and an end of the down-side current source A2, and another end of the down-side current source A2 is grounded. A control end CON is disposed between the up-side switch UP and the down-side switch DOWN. The traditional charge pump circuit 10 is formed according to the connection relationship between aforesaid components, and can adjust a voltage Va1 of the control end CON according to turning on/off of the up-side switch UP and the down-side switch DOWN to output the voltage Va1 of the control end CON.
The up-side switch UP is controlled by an up-side control signal CS1, and the down-side switch DOWN is controlled by a down-side control signal CS2. Therefore, in order to increase the voltage Va1 of the control end CON (i.e. the control end CON is charged), for example, the up-side control signal CS1 is high voltage level and the down-side control signal CS2 is low voltage level, at this time, the up-side switch UP is turned on and the down-side switch DOWN is turned off. The first current I1 of the current source A1 flows through the up-side switch UP to the control end CON to increase the voltage Va1 of the control end CON. In order to decrease the voltage Va1 of the control end CON (i.e. the control end CON is discharged), for example, the down-side control signal CS1 is low voltage level and the down-side control signal CS2 is high voltage level. At this time, the up-side switch UP is turned off and the down-side switch DOWN is turned on. The second current I2 of the current source flows through the down-side switch DOWN to ground to decrease the voltage Va1 of the control end CON. Accordingly, the charge pump circuit 10 can stabilize the voltage Va1 of the control end CON by the first current I1 and the second current I2.
As shown in FIG. 1, during the process from initiating operation of the charge pump circuit 10 to stabilizing the voltage Va1 of the control end CON, the voltage Va1 of the control end CON is gradually decreased from the power voltage VDD to a stable voltage. However, it usually takes a lot of time from the power voltage VDD to the stable voltage. If the time from initiating operation of the pump circuit 10 to stabilizing the voltage Va1 of the control end CON could be shortened, a working efficiency of the PLL can be efficiently increased.